Alternating-current-motor control.



No. 792,103 '1 PATENTED JUNE 13, 1905. G. WINTER & P. EIOHBERG.

ALTBRNATING CURRENT MOTOR CONTROL.

APPLICATION FILED NOV. 14, 1904.

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UNITED STATES Patented June 13, 1905.

PATENT OFFICE.

GABRIEL IVINTER, OF VIENNA, AUSTRIA-HUNGARY, AND FRIEDRICH EICHBERG, OFBERLIN, GERMANY, ASSIGNORS TO GENERAL ELEC- TRIC COAIPANY, A CORPORATIONOF NE YORK.

ALTERNATlNG-CURRENT-MOTOR CONTROL.

SPECIFICATION forming part of Letters Patent No. 792,103, dated June 13,1905.

Application filed November 14, 1904,. Serial No. 232,609.

To all 1.0720717, it may concern:

Be it known that we, GABRIEL WINTER, residing at Vienna, in the Empireof Austria- Hungary, and FEIEnRIoH EIOHBERG, residing at Berlin, in theEmpire of Germany, both subjects of the Emperor of Austria-Hungary, haveinvented certain new and useful Improvements inAlternating-Current-Hotor Control, of which the following is aspecification.

Our invention relates to the control of alternating-current motors ofthe type disclosed in our former application, Serial No. 1 16,692, Iiledby us March 16, 1903; and its object is to provide a simple andeflicient means for braking such motors. The type of motor disclosed inthe above application comprises three windings. One of these, which maybe called the inducing-winding, is supplied from a source of alternatingcurrent. A second winding, which may be called the induced winding andwhich is relatively movable to the first, is short-circuited on the lineof magnetization produced by the first winding and has current inducedin it by that magnetization. The third winding, which may be called theexciting-winding, produces a magnetization at an angle to that of theinducing and induced windings, and this magnetization, in combinationwith the current in the other windings, produces a motor torque. Theexciting-winding is connected in series with the induced or inducingwindings directly or through a series transfomer. The latter arrangementis preferred, since it enables the torque of the motor to be regulatedWith case. Although three windings are mentioned, the exciting-winding,as pointed out in our former application, may be combined with eitherthe inducing or induced winding.

The object of our present invention is to connect the windings of amotor of this type so that a strong braking action is secured whendesired.

Our invention consists in reversing the relative connections of theinducing and exciting windings and short-circuiting the inducing-windingon itself. This action causes the motor to act as an eflicient brake,and the braking effect may be readily controlled by means of the sameseries transformer which controls the torque when running.

Our invention will best be understood by reference to the accompanyingdrawings, in which- Figure 1 shows diagrammatically a motor of the typeabove described, in which the exciting-winding is connected directly inseries with the inducing-winding, together with a switch forestablishing braking connections in accordance with our invention; andFig. 2 shows a similar arrangement of motor and controlling-switch, butwith the exciting-winding connected in series with the inducing-windingthrough a series transformer with variable ratio.

Referring first to Fig. 1, A A represent the inducing-winding, which inoperation is connected to the line-wires L by means of a switch S. Brepresents the induced winding, which is shown diagrammatically as arotorwinding provided with commutator-brushes arranged and connected toshort-circuit the winding on the line of magnetization produeed by theinducing-winding A A. C C represent the exciting-winding, arranged toproduce a magnetization at right angles to that of the induced andinducing windings. The winding C is in the arrangement shown connecteddirectly in series with the winding A. The switch S has twopositions-for running and for braking, (indicated by the letters r and7).) lVith the switch in the position 1' it will be seen that thecurrent passes from the upper line-wire through the inducing-winding AA, through the eXciting-wind-' ing C C, to the lower line-wire. Thefield produced by the windingC C acting upon the currents in the inducedwinding B produces the motor torque. Now if switch S is moved to thebraking position, as indicated by Z), the windings A and C are still inseries, but are connected to the terminals of the resistance R insteadof to the line-wire. This connection, as has been heretofore said,produces a strong and eflective braking action, 'which may be controlledby varying the amount of resistance R in the short circuit.

In the arrangement shown in Fig. 2 the eX- citing-winding C is notconnected directly in series with the inducing-winding A A, but isconnected to the secondary of a series transformer T with variableratio.v By means of this transformer thestrength of the field producedby the exciting-winding C may be varied and the motor torque therebyregulated. When the switch S is in the braking position, as indicated byZ2, the connections of the exciting-winding C are reversed relative tothe secondary of the transformer T, and consequently relative to theinducing-winding A. The inducing-winding A is short-circuited throughthe resistancesR, as before, with the primary of transformer T in theclosed cir-' cuit. As before, this connection produces an efficientbraking action, which may be regulated in amount by varying the ratio ofthe series transformer T or by varying the amount of resistance R, as inFig. 1, or both.

Although for the sake of simplicity the exciting and inducing windingshave been shown as independent, it will be understood that theexciting-winding may be combined with either the inducing or inducedwinding, as fully set forth in our former application, and when the termexciting-winding is used in the appended claims it will be understoodthat it includes any winding to produce a magnetization at an angle tothat of the inducing or induced windings whether independent of thosewindings or combined with one of them. Furthermore, although in Fig. lwe have shown the resistance connected in series with both windings Aand C and in Fig. 2 have shown it connected in series with Winding Aalone, it is evident that the braking resistance may be placed in serieswith any of the three windings with the same result in each case, sinceall three windings are inductively connected in series, as the windingsA and B correspond to the primary and secondary of a transformer, whilethe winding C is connected in series with the winding A or B eitherdirectly or through a transformer. Accordingly we do not desire to limitourselves to the particular construction and arrangement here shown, butaim in the appended claims to cover all modifications which are withinthe scope of our invention.

What we claim as new, and desire to secure by Letters Patent of theUnited States, is

1. In an alternating current motor, an inducing-winding, an ind ucedwinding relatively movable thereto and short-circuited on the line ofmagnetization produced thereby, an exciting-winding arranged to producea second magnetization at an angle to the first, and means for reversingthe relative connections of said exciting-winding and short-circuitingsaid inducing-winding.

2. In an alternating-current motor, an inducing-Winding, an inducedwinding relatively movable thereto and short-circuited on the line ofmagnetization producedthereby, a transformer having its primary inseries with one of said windings, an exciting-winding connected to thesecondary of said transformer and arranged to produce a magnetization atan angle to the first, and means for reversing the relative connectionsof said exciting-winding and short-circuiting said inducing-winding.

3. In an alternating-current motor, an inducing-winding, an inducedwinding relatively movable thereto and short-circuited on the line ofmagnetization produced thereby, a transformer having its primary inseries with one I of said windings, an exciting-winding connected to thesecondary of said transformer and. arranged to produce a magnetizationat an angle to the, first, means for reversing the relative connectionsof said exciting-winding and shoi't-circuiting said Y inducing-winding,and means for varying the ratio of transformation of said transformer.

4:. In an alternating-current motor, an inducing-winding, an inducedwinding relatively movable thereto and short-circuited on the line ofmagnetization produced thereby, a transformer having its primary inseries with one of said windings, an exciting-winding connected to thesecondary of said transformer and arranged to produce a magnetization atan angle to the first, and a switch adapted and arranged to connect saidinducing-winding to a source of alternating current or in shortcircuitand to reverse the relative connections of said exciting-winding.

5. In an alternating-current motor, an inducing-winding, an inducedwinding relatively movable thereto and short-cireuited on the line ofmagnetization produced thereby, an exciting-winding arranged to producea second magnetization at an angle to the first, and means for reversingthe relative connections of said exciting-winding and short-circuitingsaid inducing-winding through a variable resistance.

6. In an alternating-current motor, an inducing-winding, an inducedwinding relatively movable thereto and short-circuited on the line ofmagnetization produced thereby, a transformer having its primary inseries with one of said windings, an exciting-winding connected to thesecondary of said transformer and arranged to produce a magnetization atan angle to the first, and means for reversing the relative connectionsof said exciting-winding and short-circuiting said inducing-wind- 1magnetization at an angle to the first, means for reversing the relativeconnections of said exciting-winding and short-circuiting saidinducing-winding, and means for connecting a resistance in series withone of said windings.

8. In an alternating-current motor, an ind ucing-winding, an inducedwinding relatively movable thereto and short-circuited on the line ofmagnetization produced thereby, a transformer having its primary inseries with one of said windings, an exciting-Winding connected to thesecondary of said transformer and arranged to produce a magnetization atan angle to the first, means for reversing the

